Led lighting tube device and method

ABSTRACT

An LED lighting tube including a heat-dissipating tubular envelope having an LED assembly directly affixed to an inner surface of the heat-dissipating tubular envelope. A method of making an LED lighting tube by providing a heat-dissipating tubular envelope and affixing an LED assembly directly to an inner surface of the heat-dissipating tubular envelope with an adhesive layer. A method of providing heat-dissipation without a heat sink in an LED lighting tube by providing a heat-dissipating tubular envelope, affixing an LED assembly directly to an inner surface of the heat-dissipating tubular envelope with an adhesive layer, and dissipating heat through the heat-dissipating tubular envelope.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates to light-emitting diode (LED) basedlighting tubes, and in particular to LED based lighting tubes forserving as replacements for fluorescent lighting tubes.

2. Background Art

LED lighting tubes have for many years been used as energy efficientreplacements for conventional fluorescent lighting tubes. A typical LEDlighting tube includes an LED assembly enclosed at least partiallywithin a clear or frosted tubular envelope. The LED assembly includes aplurality of LEDs in electrical connection with a circuit board, whichis usually attached to a heat sink or other heat dissipating device. Theopen ends of the tubular envelope are usually closed by end caps, whichalso provide electrical connection between the LED assembly and a powersupply.

The mounting of the LED assembly within the tubular envelope engendersproblems that have not been solved in the prior art. In many exemplarylighting tubes, such as those disclosed in U.S. Pat. No. 7,510,299 toTimmermans, et al., and U.S. Pat. No. 7,053,557 to Cross, et al., theLED assembly is attached to supports that are suspended from the endcaps or from the interior of the envelope. This configuration is costlyto construct and difficult to keep in proper alignment during shippingand installation of the LED lighting tube. It also limits the arc ofillumination, since light emitted by the LEDs is blocked by thesupporting structures, the circuit board, and the heat sink. In otherexemplary lighting tubes, such as that disclosed in U.S. Pat. No.7,815,338 to Siemiet, et al., the LED assembly interrupts thecircumference of the tubular envelope, with the heat sink being situatedoutside of the envelope. In cross section, the envelope forms anincomplete circle, with free edges attaching to the heat sink or toanother part of the LED assembly. This type of design excludes the useof desirable but delicate envelope materials such as thin glass orbrittle plastic, because it is difficult or impossible to durably attachtheir free edges to the LED assembly without breakage. The design alsolimits the arc of emitted light with the bulky opaque structure of theheat sink. There is a need for an LED lighting tube of light and simpleconstruction.

LED lighting tubes, and lighting tubes of all types, typically include afrosted film on the tubular envelope, to diffuse and reduce theharshness of the emitted light. Typical films include paints or powders,which are difficult to apply evenly, and which provide no mechanicalprotection for the envelope. There is a need for a lighting tube filmthat is readily applied in a consistent manner, and which protects thelighting tube.

SUMMARY OF THE INVENTION

The present invention provides for an LED lighting tube including aheat-dissipating tubular envelope having an LED assembly directlyaffixed to an inner surface of the heat-dissipating tubular envelope.

The present invention provides for a method of making an LED lightingtube, by providing a heat-dissipating tubular envelope, and affixing anLED assembly directly to an inner surface of the heat-dissipatingtubular envelope with an adhesive layer.

The present invention also provides for a method of providingheat-dissipation without a heat sink in an LED lighting tube byproviding a heat-dissipating tubular envelope, affixing an LED assemblydirectly to an inner surface of the heat-dissipating tubular envelopewith an adhesive layer, and dissipating heat through theheat-dissipating tubular envelope.

DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention are readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanying drawingswherein:

FIG. 1A shows a bottom elevation of an LED lighting tube according tothe present invention, FIG. 1B shows an exploded view of an exemplaryLED tube, and FIG. 1C shows a longitudinal section of the LED lightingtube;

FIG. 2A shows a cross section of an LED lighting tube according to thepresent invention, including an LED board affixed directly to theenvelope, with components not drawn to scale, and FIG. 2B shows a crosssection of an LED lighting tube, including an LED assembly with aheat-dissipating base, affixed to the envelope, with components notdrawn to scale;

FIG. 3A shows a tubular envelope and a plastic film sleeve, prior toheat treatment, and FIG. 3B shows a cross section of a tubular envelope,including a light diffusing and protective film according to the presentinvention, with components not drawn to scale;

FIG. 4 is a side perspective view of an LED lighting tube including abutton safety switch; and

FIG. 5A is a diagram of single input for a mechanical safety switch,FIG. 5B is a diagram of a double input for a mechanical safety switch,FIG. 5C is a diagram of a single input for an electronic safety switch,and FIG. 5D is a diagram of a double input for an electronic safetyswitch.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for LED lighting tubes, methods ofmaking, methods of providing heat-dissipation without the need for anadditional heat sink, and methods of preventing shocks to individualsinserting and removing LED lighting tubes through the use of a safetyswitch. More specifically, an LED lighting tube according to the presentinvention, generally shown at 10, includes essentially an envelope 12,preferably tubular in form, having an inner surface 14 defining an innerspace 20 and being preferably circular in cross-section, and an exteriorsurface 46, opposite the inner surface 14, as shown in FIGS. 1A and 1B.The LED lighting tube 10 has a longitudinal axis designated as L in FIG.1A. The inner space 20 preferably contains ambient atmosphere, but canalternatively be filled with any gas required for a specific use, aswill be determined by one skilled in the art.

The envelope 12 is preferably constructed of glass as a single tubularunit. Alternatively, the envelope 12 can be constructed of any suitableclear or translucent plastic. The envelope 12 is a heat-dissipatingenvelope.

An LED assembly 16, extending along the longitudinal axis L of theenvelope 12, includes an LED board 18, which has an upper surface 22bearing an attached LED array 24. The LED array 24 includes a pluralityof LEDs 26 in electrical interconnection. The LED board 18 containselectrical connections (not shown) among the LEDs 26, and an electricalconnection to a power source. Preferably, the LED board 18 is anintegrated circuit board, but it can alternatively be a wired circuitboard.

The LED assembly 16 is affixed directly to the inner surface 14 of theenvelope 12, preferably by an adhesive layer 40. The direct affixationof the LED assembly 16 to the inner surface 14 of the envelope 12provides an LED lighting tube 10 that is both structurally robust andsimple in construction, because it requires no supporting hardware oralignment procedure for suspension of the LED assembly 16 within theenvelope 12. Direct mounting to the envelope 12 also allows the envelopeitself to act as a heat-dissipating device, eliminating the need for aheat sink. An LED lighting tube 10 according to the present inventionalso provides a wider arc of emitted light than LED lighting tubes thatincorporate a bulky heat sink that interrupts the envelope 12 with anextensive opaque region. Arcs as broad as 330° are produced by LEDlighting tubes of the present invention. The elimination of a heat sinkand supporting hardware, and the resulting reduction in complexity andincrease in the arc of illumination, are all advantages of the presentinvention over LED lighting tubes of the prior art.

In the LED array 24, the LEDs 26 are preferably arranged as at least onelinear string of LEDs 26, connected in series, although parallelconnections are also contemplated. The LED array 24 can include aplurality of linear strings of LEDs 26 (not shown), the stringspreferably being connected in parallel. Non-linear clusters of LEDs 26,arranged in any suitable distribution along the length of the LED board18, are also within the scope of the present invention.

The preferred LED 26 is a surface mount LED, most preferably SMD 4014.LEDs of other types, as well as LEDs emitting wavelengths of light otherthan white, are also within the scope of the invention. The other colorsinclude, but are not limited to, pink, blue, yellow, green, red, orange,infrared, and ultraviolet.

The LED board 18 also includes a first end 28 in electricalcommunication with a first electrical connector 50 and a second end 30in electrical communication with a second electrical connector 52, eachelectrical connector 50, 52, being connectable, to an electricalreceptacle of a light fixture. Preferably, the connection is to anelectrical receptacle made by bi-pin male connectors situated in an endcap 13, for connecting to corresponding conventional fluorescent tubesockets (not shown).

The LED board 18 can optionally include voltage and current regulatingcircuits, preferably in the form of integrated circuits incorporatedinto the LED board (not shown). Alternatively, or additionally, one ormore of these circuits, if included, can be situated at any othersuitable location within the LED lighting tube 10, such as the end cap13. In an exemplary embodiment shown in FIGS. 1B and 1C, regulatorycircuits are distributed among drivers 17, each driver being situatedwithin a protective sleeve 19 adjacent to each end cap 13. Thecomponents and layout of any included voltage and current regulatingcircuits will depend on the voltage and current supply and needs of aparticular LED lighting tube 10, and are readily determined by oneskilled in the art. In another alternative embodiment, no voltage orcurrent regulating circuits are included in the LED lighting tube 10,and, if required, they are situated at any suitable site exterior to theLED lighting tube 10, such as a lighting fixture.

The LED board 18 preferably extends along approximately the entirelength of the LED assembly 16, but it can alternatively extend alongonly a portion of the length. The LED board 18 can additionally oralternatively cover one or both lateral sides 32 of the LED assembly(not shown), to provide diverse angles of emitted light.

In the preferred embodiment, the LED board 18 itself provides sufficientheat dissipation to prevent degradation of the structure or performanceof the LEDs 26, and no heat dissipating base or other heat sinkstructure is required. Aluminum construction of the LED board 18 istherefore preferred, although other heat-conducting compositions canalternatively be used, such as, but not limited to, aluminum, aluminumalloy, steel, steel alloy, copper, and copper alloy.

The present invention also encompasses alternative embodiments that doinclude a heat-dissipating base 34, as shown in FIG. 2B. Theheat-dissipating base 34 is preferably constructed of aluminum foil, butcan also consist of any suitable thickness of aluminum, aluminum alloy,steel, steel alloy, copper, copper alloy, mixtures thereof, or anyheat-dissipating material known in the art. The heat-dissipating base 34can be affixed to the lower side 36 of the LED board 18, i.e., the sideopposite the LED array 24, by means of adhesive, welding, or any otherjoining means known in the art. Alternatively, the heat-dissipating base34 can be formed as an integral component (not shown) of the LED board18. In embodiments having a heat-dissipating base 34, the preference fora heat-dissipating LED board 18 is diminished, and less heat-conductivecompositions such as polycarbonate can be utilized in the constructionof the LED board 18.

The LED assembly 16 can be affixed to the inner surface 14 of theenvelope 12 by means of an adhesive layer 40 as shown in FIGS. 2A and2B. The adhesive layer can include epoxy resin, silicone adhesive(preferably neutral cure silicone adhesive), any double-sided adhesivetape, or any other adhesive of which as sufficient strength anddurability, as well as sufficient heat transfer properties. In thepreferred embodiment, which lacks a heat-dissipating base 34, a lowerside 36 of the LED board 18 is affixed directly to the inner surface 14of the envelope 12, as shown in FIG. 2A. In alternative embodimentsincluding a heat dissipating base 34, the lower side 38 of the base 34is affixed to the inner surface 14 of the envelope 12, as shown in FIG.2B. The adhesive layer 40 covers as much area of the inner surface 14 asrequired to secure the LED assembly 16, and can if necessary, extendbeyond the edges of the LED assembly 16 (not shown).

The LED assembly 16 is preferably affixed to the envelope 12 at a pointopposite the direction in which light emission is to be directed.Multiple LED assemblies 18 can also be affixed at different points on asingle envelope 12, to increase the arc and intensity of light emission(not shown).

An LED lighting tube 10 according to the present invention can be of anydiameter and length known in the art, and preferably of diameters andlengths identical to those known for conventional fluorescent tubes.These include, but are not limited to, diameters of ¼″, ½″, ⅝″, 1″, and1½″ known in the art, respectively, as T2, T4, T5, T8, and T12; andlengths of 6″, 9″, 12″, 18″, 48″, and 96″. Scaling the LED lighting tube10 to match conventional fluorescent tubes facilitates the replacementof existing fluorescent tubes with LED lighting tubes 10 according tothe present invention.

It is preferred that the LED lighting tube 10 does not includeadditional features such as additional coatings or films (other thanthose described herein) to keep the cost of the device minimal and tokeep the device easy to manufacture.

The illustrated embodiments of the LED lighting tube 10 include linearenvelopes 12 and linear LED assemblies 18, but the present inventionalso encompasses non-linear components such as envelopes 12 and LEDassemblies 18 formed as rings, loops, spirals, rectilinear shapes (notshown), and any other achievable geometric form.

The LED lighting tube 10 can further include a safety switch 60 toensure that the LED lighting tube 10 can only be operated and turned onwhen it is properly placed inside an electrical socket (such as atombstone socket), activating the safety switch 60. The safety switch 60is located at any suitable location on the end caps 13, such as betweenbi-pins 66. The safety switch 60 can be included in one end cap 13 orboth end caps 13. In one embodiment, the safety switch 60 is amechanical switch 62, shown in FIG. 4 in the shape of a button. Adiagram of the mechanical switch 62 is shown in FIGS. 5A and 5B. Inanother embodiment, the safety switch is an electronic switch 64 thatincludes a sensor connected to a circuit. A diagram of the electronicswitch 64 is shown in FIGS. 5C and 5D. Prior art LED lighting tubes useballasts, which are not required with the safety switch 60 in thepresent invention.

The present invention provides for a method of preventing shocks to anindividual inserting or removing an LED lighting tube from an electricalsocket, by an individual inserting or removing the LED lighting tube 10from an electrical socket, providing power to the LED lighting tube 10only when the safety switch 60 is activated, and preventing shocks tothe individual. The safety switch 60 can be either the mechanical switch62 or electronic switch 64 described above. By using the safety switch60, injuries and deaths can be prevented to individuals inserting orremoving the LED lighting tube 10 because power is not supplied untilthe safety switch 60 is fully activated upon insertion, and power is cutas soon as the safety switch 60 is deactivated upon removal. This methodcan also include any of the other steps described herein.

The present invention also provides a method for making an LED lightingtube 10, including the steps of providing a tubular envelope 12,situating an LED assembly 16 on an inner surface 14 of the of thetubular envelope 12, and affixing the LED assembly 16 directly to theinner surface 14 of the tubular envelope 12 with an adhesive layer 40.Each of these steps has been described above. Preferably, the LEDlighting tube 10 does not include other elements than what is describedherein.

The present invention also provides for a method of providingheat-dissipation without a heat sink in an LED lighting tube 10, byproviding a tubular envelope 12, affixing an LED assembly 16 directly toan inner surface 14 of the tubular envelope 12 with an adhesive layer40, and dissipating heat through the tubular envelope 12. Also, asdescribed above, the materials of the LED board allow it to provideheat-dissipation to the envelope as well. Preferably, the LED lightingtube 10 does not include other elements than what is described herein.

The present invention also includes a method for adding a film to alighting tube, such as an LED lighting tube 10, with a light-diffusingand protective film 48. The process is shown in FIGS. 3A and 3B. Theprocess includes the steps of situating a plastic film sleeve 44 aboutan exterior surface 46 of an envelope 12 of a lighting tube;heat-treating the plastic film sleeve 44; and bonding the plastic filmsleeve 44 as a light-diffusing and protective film 48 upon the exteriorsurface 46 of the envelope 12. The lighting tube can be a lighting tube10 according to the present invention, or any other suitable lightingtube or bulb (not shown). This process produces a light-diffusing andprotective film 48 that is uniform, and that provides physical supportfor the envelope 12, to reduce the risk of breakage, and the scatteringof glass shards should breakage occur.

The preferred material for the film sleeve 44 is milk-white poly film,which, after heat treatment, produces a light-diffusing and protectivefilm 48 with a milk-white frosted finish on the exterior surface 46 ofthe envelope 12. An exemplary film material is polyethyleneterephthalate, and an exemplary heat treatment is treatment at 85° C.

The plastic film sleeve 44 can be of any shape and circumference thatsufficiently conforms to the circumference of the envelope 12 to providea tightly bonded, wrinkle-free film after heat treatment. Tinted plasticfilm sleeves 44 can alternatively be utilized, to add warmer, cooler, ordecorative colors to the emitted light. The plastic film need not beprovided as a film sleeve 44 but can instead be provided as an opensheet that is wrapped about the exterior surface 46 of the envelope 12prior to heat treatment. The present invention provides for an LEDlighting tube 10 including the plastic film sleeve 44 attached to theexterior surface 46 of the envelope 12.

The film-coating process of the present invention is not limited to LEDlighting tubes 10, and is applicable to other types of lighting tubes,such as conventional fluorescent tubes.

The present invention also provides a method for illuminating a spacewith an LED lighting tube 10, including the steps of providing a tubularglass envelope 12, situating an LED assembly 16 on an inner surface 14of the of the envelope 12, affixing the LED assembly 16 to the innersurface 14 of the envelope 12 with an adhesive layer 40, connecting afirst electrical connector 50 to a first end 28 of the LED assembly 16,connecting a second end 30 of the LED assembly 16 to a second electricalconnector 52, and connecting the first and second electrical connectors52, 53, to a lighting fixture (not shown). Preferably, the LED lightingtube provides up to 330° arcs of light.

In its preferred embodiments, an LED lighting tube 10 according to thepresent invention is simpler, sturdier, and more broadly illuminatingthan LED lighting tubes of the prior art, because it includes an LEDassembly 16 that is affixed directly to the inner surface 14 of theenvelope 12, and requires no heat dissipating base 34. Embodiments ofthe LED lighting tube 10 that additionally include a light diffusing andprotective film 48 are safer than those of the prior art, which includeonly surface deposited powders and paints.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology, which has been used is intended tobe in the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims, the inventioncan be practiced otherwise than as specifically described.

What is claimed is:
 1. An LED lighting tube, comprising: aheat-dissipating tubular envelope including an LED assembly directlyaffixed to an inner surface of said heat-dissipating tubular envelope.2. The LED lighting tube of claim 1, wherein said heat-dissipatingtubular envelope is made of a material selected from the groupconsisting of glass and plastic.
 3. The LED lighting tube of claim 1,wherein said LED assembly is further defined as an LED board having anLED array attached to an upper surface, said LED array including aplurality of LEDs in electrical interconnection.
 4. The LED lightingtube of claim 3, wherein said LED board includes a first end inelectrical communication with a first electrical connector and a secondend in electrical communication with a second electrical connector,wherein said first electrical connector and second electrical connectorare in connection with an electrical receptacle of a light fixture. 5.The LED lighting tube of claim 3, wherein said LED board includesvoltage and current regulating circuits.
 6. The LED lighting tube ofclaim 3, wherein said LED board covers at least one lateral side of saidLED assembly.
 7. The LED lighting tube of claim 3, wherein said LEDboard further includes a heat-dissipating base affixed to a lower sideof said LED board.
 8. The LED lighting tube of claim 7, wherein saidheat-dissipating base is made of a material chosen from the groupconsisting of aluminum foil, aluminum, aluminum alloy, steel, steelalloy, copper, copper alloy, and mixtures thereof.
 9. The LED lightingtube of claim 7, wherein said LED board is made of polycarbonate. 10.The LED lighting tube of claim 1, wherein said LED assembly is directlyaffixed to said inner surface with an adhesive layer.
 11. The LEDlighting tube of claim 10, wherein said adhesive layer is a materialchosen from the group consisting of epoxy resin, silicone adhesive, anddouble-sided adhesive tape.
 12. The LED lighting tube of claim 1,wherein said LED assembly includes an LED board made of a materialchosen from the group consisting of aluminum, aluminum alloy, steel,steel alloy, copper, and copper alloy.
 13. The LED lighting tube ofclaim 1, wherein said LED lighting tube provides up to 330° arcs oflight.
 14. The LED lighting tube of claim 1, wherein saidheat-dissipating tubular envelope further includes a heat-treatedplastic film attached to an exterior surface.
 15. The LED lighting tubeof claim 15, wherein said heat-treated plastic film is made ofpolyethylene terephthalate.
 16. A method of making an LED lighting tube,including the steps of: providing a heat-dissipating tubular envelope;and affixing an LED assembly directly to an inner surface of theheat-dissipating tubular envelope with an adhesive layer.
 17. The methodof claim 16, wherein the adhesive layer is a material chosen from thegroup consisting of epoxy resin, silicone adhesive, and double-sidedadhesive tape.
 18. A method of providing heat-dissipation without a heatsink in an LED lighting tube, including the steps of: providing aheat-dissipating tubular envelope; affixing an LED assembly directly toan inner surface of the heat-dissipating tubular envelope with anadhesive layer; and dissipating heat through the heat-dissipatingtubular envelope.